The practice of removing hair from the body extends back through recorded history. A number of different methods to remove hair have been used. Shaving hairs or whiskers off at skin level using a sharpened blade, or razor, is probably the best known of such methods.
Topical compositions, or shaving aids are continually being developed not only to make shaving easier, but, to achieve a closer, less skin irritating shave. One such composition is a shaving cream. Shaving creams are used particularly by men for removing beard growth from their faces; aerosol shaving creams being the best known. Aerosol shaving creams, usually packaged in pressurized metal cans, are white, voluminous, creamy foams, are disclosed in U.S. Pat. Nos. 3,330,730, Hernandez, issued Jul. 11, 1967; 3,655,865, Murphy, issued Apr. 11, 1972 and 3,923,970, Breuer, issued Dec. 2, 1975.
A relatively recent shaving composition is the post-foaming shaving gel. These compositions are designed to be dispensed from the can as a clear, translucent gel, which is converted to a foam when rubbed into the palm or against the face. Such compositions are described in U.S. Pat. Nos. 3,541,581, Monson, issued Nov. 17, 1970; 4,528,111, Su, issued Jul. 9, 1985; 4,957,732, Grollier et al., issued Sep. 18, 1990; 5,034,220, Helioff et al, issued Jul. 23, 1991; British patent applications GB 1,279,145, published Jun. 28, 1972 and GB 1,444,334, published Jul. 28, 1976; and PCT Application WO 91/07943, Chauduri, published Jun. 13, 1991; all such U.S. Patents herein by reference.
Since shaving, particularly daily shaving, can irritate the skin around the neck and face manufacturers of the shaving compositions often add ingredients to minimize skin irritation, and impart good skin feel both during and after shaving. These ingredients include humectants, emollients, and moisturizers. Such ingredients include aloe, menthol, lanolin, yucca, silicones, and other ingredients known for use in cosmetic compositons. Additional ingredients may be 4,957,732, to impart therapeutic benefits to the skin. These ingredients include antiseptics for treating razor cuts and nicks.
It is known in the art that silicone oils form a protective coating on the skin by filling the crevices and follicular openings of the skin. This protective coating reduces water loss through the stratum corneum and avoids tightening of the skin. Silicones are also thought to fill the cracks and crevices in the skin, resulting in skin smoother to the touch. Therefore, shaving compositions containing silicones not only reduce razor friction, but benefit the skin as well. Silicone oils, however, are typically difficult to incorporate into typical shaving compositions due their relative hydrophobicity. Therefore, in order to incorporate silicones into a typical aqueous-based shaving compositions, they must be modified to increase their hydrophilicity.
The preferable form silicones take when incorporated in shaving compositions are actually silicone polymers having acyloxyalkyl groups attached to the silicone backbone. These silicone copolymers, or polyorganosiloxanes, are hydrophilic non-ionic surfactants which can be easily incorporated into aqueous-based shaving composition. Silicone copolymer nonionic surfactants are disclosed in the art. Dow Corning's publication, A Unique Marketing Proposition, copyrighted 1987, discloses using Dow Corning 193 Dimethicone Copolyol (a dimethicone copolyol) in shaving creams. U.S. Pat. No. 5,034,220, Helioff et al. discloses using non-volatile polyethersiloxane copolymers, in shaving compositions for lubricating and protecting the skin during shaving. PCT Application WO 91/07943 discloses using polysiloxane polyether copolymers, i.e. dimethicone copolyols, in a shaving gel to improve the clarity and brightness of the gel.
The above mentioned art discloses adding a second non-ionic surfactant to shaving gels containing the silicone copolymer surfactant. The secondary non-ionic surfactant stabilizes the gel and improves the foam consistency of the lather created when the gel is rubbed onto the face. Furthermore, these secondary non-ionic emulsifiers act as wetting agents, thereby promoting good rinsing of the shaving lather from the razor and the skin. Typical secondary non-ionic surfactants include Oleth-10, Oleth-20, Ceteth-10, Ceteth-20; see PCT Application WO 91/07943.